Name:
Archaeocidaris illinoisensis Age: Mississippian Formation: St. Louis Formation Location: St. Louis, Missouri Size: Plate is 6.6 inches across This specimen is not for sale Click here for similar specimens that are for sale
This is a very rare echinoderm fossil. It is a plate of FOUR Archaeocidaris illinoisensis from the Mississippian of St. Louis. Fossil echinoids from the St. Louis area are famous around the world and have been extremely sought-after by collectors for decades. These urchins were found YEARS ago, and just now prepared. These spiny urchins are larger than the Lepidocidaris found in the Mississippian Warsaw Formation, and are OLDER than the Pennsylvanian Archaeocidaris from Texas. These four urchins themselves are complete with MANY barbed spines still intact. Most of the types of urchins from this site have smooth spines (there are three species!), and ones with the barbed spines are uncommon. The echinoids display well on the large, semi-oval plate of matrix that also has other partial urchins preserved. This is a very rare multiple example of Mississippian echinoids from the St. Louis Formation